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What happen after paging

+2 votes

When a UE is in idle mode DRX, if it receive a paging message, it will establish RRC connection and become RRC-Connected
1.Will its DRX mode become connected when it become RRC-Connected?
2.Will it turn to RRC-Idle when it received packet and there's no other packet coming?
3.If a UE is in connected mode DRX, will it still remain RRC-Connected when it's in sleep mode(opportunity for DRX)?

posted Oct 18, 2017 by Yu Rin Lin

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1 Answer

+1 vote
Best answer

The objective of DRX is reduce the power consumption at UE so that UE's battery will run long time compare to the situation when DRX is not being used. There are mainly two kinds of DRX. The one which is used during RRC connected mode is known as connected mode DRX (C-DRX) and the other one that is used in Idle mode is known as Idle mode DRX.

In case of idle mode DRX, eNodeB would not be aware of UE's location and whenever any data arrives at core network for that UE, network triggers paging message. One foremost important point here is Paging message is not triggered immediately from the network , actually paging message is sent by network at the defined paging frame and paging occasion.

Now coming to your question.

  1. After receiving the paging message from network, UE establishes radio connection with the eNodeB and enters into the RRC connected mode. Again in RRC connected mode, if there is no data transmission for the configured time interval, UE enters into C-DRX mode. In this stage, UE will be in RRC Connected and C-DRX mode.

  2. An eNodeB runs user inactivity timer for an UE when it observes that there is no data transmission happened for a particular UE for the configured time internal. Once that timer gets expired, eNodeB releases radio connection with UE and UE enters into RRC-IDLE mode. In this stage, UE will be in RRC Idle and DRX mode.

  3. Answer is Yes. In case of C-DRX mode, UE will be in RRC Connected mode.

answer Oct 20, 2017 by Ganesh
So if there is a UE in RRC-Idle and Idle mode DRX, when it receiving the paging message from network, it will become RRC-Connected and C-DRX, until eNB observes that there is no data transmission happened for UE and the timer gets expired, then UE will turn back to RRC-Idle and Idle mode DRX, am I correct?
Similar Questions
0 votes

When UE is in idle mode DRX and receive paging message, it will establish RRC connection, and when it become RRC-Connected, what happen next?
Does it change to connected mode DRX? or it will turn to RRC-Idle after receiving packet?

And I have another question
when a UE is in connected mode DRX, will it remain RRC-Connected when it turn to sleep mode(opportunity for DRX)?

0 votes

Consider if eNB is sending DRX cycles to your UE and therefore you will be not listening to PDCCH. Now if MME sends paging messages of that UE, then how UE will be able to receive the paging message? After DRX cycles UE can start listening but MME might have stopped sending paging messages. How this is handled in LTE???

+4 votes

When we will construct a RRC paging message with multiple paging records?
In which scenario I need to construct a RRC paging message message with multiple paging records.Suppose we have 10 UEs in idle mode and DL data notification is comming for 5 UEs at the same time,then how mme will send S1AP paging message(i.e one by one for each UE or all the message at once).If ENB is receiving all the four S1AP paging message then how RRC has to process the S1AP paging messages and how it should construct the RRC paging message (i.e whether it should send one paging record for one pcch message or it should send multiple records in one PCCH message?if multiple records then how to send the UE_ids to MAC and RLC?).

+4 votes

In which scenario we will create multiple paging records in paging message and sent it to UE.
Actually RRC will receive one S1AP paging message for one UE.HOW and WHEN RRC will create RRC paging message with Multiple UE paging Records in one PCCH message .

+3 votes

PagingUE-Identity ::= CHOICE {
imsi IMSI,

As pagingUE identity should contain any one of these in paging message so how MME decides which one to send, though for security purpose MME prefers t-o send send S-TMSI but in which scenarion MME wil use imsi as paging ue identity.

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